package edu.hawaii.duedates.libraries;

import com.meterware.httpunit.GetMethodWebRequest;
import com.meterware.httpunit.HttpUnitOptions;
import com.meterware.httpunit.WebConversation;
import com.meterware.httpunit.WebForm;
import com.meterware.httpunit.WebRequest;
import com.meterware.httpunit.WebResponse;
import com.meterware.httpunit.WebTable;

import edu.hawaii.duedates.Library;

/**
 * UHMLibrary.class
 * UHMLibrary enables the communication between our DueDates interface and the 
 * physical UHM Library System. It is also responsible for retrieving the 
 * required information, given the parameters passed by DueDates.
 *  
 * @author Anthony Du, Vincent Leung 
 *
 */
public class UHMLibrary extends Library {
  
  /**
   * Constructor for creating a library and setting user's credentials.
   * @param n String of library's name.
   * @param id String of user's id.
   * @param key String of user's key.
   */
  public UHMLibrary(String n, String id, String key) {
    super(n, id, key);
  }
  
  /**
   * Attempts to login to UH Manoa Library system.  
   * @param id The UH user ID. 
   * @param lastName  The UH user's last name. 
   * @return The WebConversation instance after successful login. 
   * @throws Exception If login was not successful with these credentials. 
   */
  @Override
  public WebConversation logIntoLibrary(String id, String lastName) throws Exception {
    String url = "http://uhmanoa.lib.hawaii.edu/cgi-bin/Pwebrecon.cgi?DB=local&PAGE=pbLogon";
    // UH Library website has bogus JavaScript code.
    HttpUnitOptions.setExceptionsThrownOnScriptError(false);
    // create the conversation object which will maintain state for us
    WebConversation conversation = new WebConversation();
    WebRequest request = new GetMethodWebRequest(url);
    WebResponse response = conversation.getResponse(request);
    WebForm form = response.getFormWithName("logonpage");
    form.setParameter("BC", id);
    form.setParameter("LN", lastName);
    form.submit();
    response = conversation.getCurrentPage();
    if (response.getText().contains("Sorry, Login unsuccessful")) {
      throw new Exception("Error while logging in to UH Library");
    }
    return conversation;
  }
  
  /**
   * Given a logged in user to the UH Library site, provides info about their library books. 
   * @return A String containing information about their books.
   * @throws Exception If problems occur parsing the site pages. 
   */
  @Override
  public String getLibInfo() throws Exception {
    String uhSiteNoItemString = "You have no items checked out.";
    try {
      WebConversation conversation = this.logIntoLibrary(getId(), getKey());
      WebResponse response = conversation.getCurrentPage();
      WebForm form = response.getForms()[0];
      if (uhSiteNoItemString.equals(form.getText())) {
        return "No items checked out";
      }
      else {
        // Assume the first table is the one we need. Not true in general.
        WebTable table = response.getTables()[0];
        String bookInfo = table.getCellAsText(1, 1);
        return "At least one book is checked out: " + bookInfo;
      }
    }
    catch (Exception e) {
      throw new Exception("Error getting UH Book info", e);
    }
  }
}